It could very well be one of the biggest policing jobs Broward authorities have ever tackled.

When the Organization of American States General Assembly begins in a few days at the Broward County Convention Center, representatives of more than 26 local, state and federal authorities will be running a massive security operation in Fort Lauderdale.

Their challenge: Find the right balance between keeping the public safe and not stifling the rights of protesters, who could number in the thousands.

"We anticipate a peaceful weekend," said Fort Lauderdale police Sgt. Andy Pallen. "Our job is to facilitate the security of the dignitaries as well as people's freedom of speech and their right to have their words heard."

Law enforcement agencies have conducted field training, developed detailed strategies and rehearsed countless "What if?" scenarios so that nothing -- be it a terrorist attack or violent protests-- takes them by surprise.

The agencies are releasing few specifics about security plans but say one thing is certain: They don't want a repeat of the 2003 Free Trade Area of the Americas protests in Miami, when police were heavily criticized for what protesters said was excessive force in crowd control.

"We learned a lot from FTAA," said Ed Moreno, special agent in charge at the State Department's Diplomatic Security Service field office in Miami. "We can handle just about anything."

The OAS security operation will be one of the biggest in the United States this year, on par with events such as the Super Bowl and the United Nations General Assembly in New York, Moreno said.

The massive event comes at a hefty price. Fort Lauderdale's latest cost estimate for a worst-case scenario -- heavy protests, high security for days -- comes to $6.7 million, with $2.8 million of that covering assistance from other local police departments.

Each law enforcement agency will have certain security responsibilities during the conference, scheduled for June 5-7.

For example:

The State Department's Diplomatic Security Service will be in charge of protecting visiting foreign dignitaries and participating U.S. officials -- including U.S. Secretary of State Condoleezza Rice and President Bush.

Fort Lauderdale police will focus on areas outside Port Everglades, including the hotels where the estimated 2,000 to 3,000 people in town for the conference will be staying.

The Coast Guard will handle security on the waterways.

The Broward Sheriff's Office will focus on the convention center and Port Everglades.

A security zone will be set up at Port Everglades, restricting access to those with OAS credentials. There will also be a security fence around the convention center.

Authorities don't expect protests on the scale of those at the FTAA summit, but they're planning, just in case. One of their "What if?" scenarios centered on mass arrests, in which scores of protesters are taken into custody.

"You've got to be prepared for the worst," Moreno said.

In anticipation of protests, Fort Lauderdale leaders passed a contentious security measure that bans weapons, signs on thick sticks, water balloons and other potentially harmful objects from certain public gatherings.

Several activist and political groups planning to protest outside the assembly have filed a lawsuit challenging those prohibitions, as well as the security zone, which they say effectively turns the port into a no-protest zone.

Groups planning to protest include the Alliance for Justice in the Americas, an umbrella organization of about 20 political and other groups. The alliance has tentative plans to stage a protest march from State Road 84 and Andrews Avenue to the Broward County Convention Center. As many as 5,000 protesters could participate, said Raymond Del Papa, an organizer for the group.

Like police, protesters want to avoid the violence they saw during the FTAA summit. "The people involved in this do not intend any violent acts," Del Papa said. "Nobody's planning any disruptions.

Police at the FTAA meeting in Miami said they faced protesters throwing rocks, bottles and other objects.

But police were scrutinized for their treatment of protesters at the FTAA meeting; there were complaints alleging dubious arrests, people being barred from attending a rally, some unarmed protesters being shot with pepper-spray balls and rubber bullets, and the destruction of personal property.

Law enforcement agencies feel that by examining FTAA security they have been able to better prepare for what lies ahead at the OAS assembly.

"We've incorporated everyone else's experience into our plans," said Fort Lauderdale Police Chief Bruce Roberts. "Part of our job is to prepare for the worst and hope for the best."